Wing Strut Rigging issues

[Dick H]

Gentlemen: I own a 1950 PA-20 with Univair sealed wing struts. I spent yesterday trying to "correct" the strut rigging that was done by the IA/A&P at the last annual. (I also am an A&P and I/A). I placed a scissors jack under each landing gear and a jack under the tail, and leveled the airplane I/A/W Piper Service Memo #20. At the completion, I thought I had done a good job. The bubble in the level was correct, the string height was correct and the wing tips were equally distant from the floor. After lowering the airplane, the right wing was 2 inches higher off the floor than the left side, and both of the right side lower strut bolts were showing about 1/2 inch more thread than the left side. In retrospect, I think that pulling and pushing on the strut upper ends, to get them in and out of their brackets, probably rotated the airplane on the landing gear bungees. (I checked the plumb bob frequently, although probably not often enough.) So, my question is; could I put a padded 2x6 cross ways, under the fuselage somewhere ahead of the landing gear and aft of the firewall, and put a scissors jack under each end of it, to level the airplane? Thereby taking the bungees out of the equation. I would really appreciate hearing from anyone who might have an idea about the 2x6, or any other part of my process! Thank you for your help!
Dick
P.S. I'm going to try this again this coming week, or as soon as I can get my helpers organized - they're kind of reluctant to do it twice!
Thanks again for any advice you can offer.

[Tom Anderson]

Dick,

I have a couple of suggestions for you. First I would suggest that you get the Rigging CD from the store. Frank Rush created a great presentation on how to rig our short wings and provides many tips. Second, I would use a digital level to set the wing dihedral, wash out and rudder and stabilizer position. The dihedral of each wing at the front spar is 2 degrees. The wash out is 2.5 degrees measured at the last aileron rib. Putting the plane on jacks should eliminate the bungee problem and if you are still concerned about it strap the gear together with one of those ratcheting straps. That way they won't move or spread apart. After you have made your adjustments, verify your plane is level and compare you dihedral and wash out from wing to wing. As important as the wing rigging is the rigging of the rudder and the stabilizer with the tail brace wires. If the rudder isn't vertical and the stabilizer horizontal your airplane won't fly straight. It's a task to get the surfaces properly aligned and the correct tension on the wires, but it can be done. Changing one wire will affect the other three wires so think about what you are doing and how it will affect the other wires before you do it. Finally, make sure your plane is properly leveled when you start and when you are done, don't pay attention to distance of the wings from the floor. Fly the plane and see how does and make small adjustments from there based on how it performs. There can be all sorts of explanations for the wings being different distances from the floor. I have used the string method and still use it to verify that the wings are equal, but it is not very accurate. The digital level if far more accurate and I have had excellent results with it.

Tom Anderson

[Tom T.]

I did like you say, and just lifted up on the wing and had a friend put a saw horse under the fusalage on each side, and then I had a 5 gallon bucket filled with water attachec to the tail tiedown. I used the rigging process from our archives and if it is not available, I still have the copies of it is you want me to send them via usps. I think maybe it might still be on Andy's site, but I have been on an inactive list since all the commothin and really dont know for sure. If ya nee thos rigging specs, let me know and I will send um for ya. My plane was a Tripacer but it was rigged abolutely perfect on the first try. I still have the 2x4 that I made for getting the angle at the wing tip if ya need it too.
Best to ya,
By the way, what ever Tom Anderson tells you, you can take to the bank. He helped me a great deal on a lot of my questions!! He is not a novice!!

[Dick H]

Thanks Tom, I'll take another swipe at this as soon as I can get my free help lined up. I kind of like Tom Andersons idea of strapping the landing gear together to get rid of the bungee interference. Thanks for the note! Dick

[Dick H]

Thanks Tom, I appreciate your thoughts. I like the idea of strapping the landing gear together to get rid of the bungee interference. I'll go look for a digital level today! BTW, I'm sure you don't remember me; I met you at the convention in Denver. Ralph Gutawski (?) asked me to come and speak to the group. I had a great time! I still have the same airplane after 15 years. Lately my flying has slowed down, but now that I'm retired I'm getting back into it. Thanks for the advice. Dick Hitt

[andya]

I believe Frank Rush rigging instructions (scanned from an old SWPC news) is on my "andy's site"

[Tom Anderson]

Dick and Tom,

Thank you for the kind words. The club has a lot or resources if we can just get them organized, but that's another story. Thanks to Andy for supplying much of the data in the mean time. I do recommend the rigging CD from the store if you are looking for instructions, though. Franks explanation and the photos are worth the $20. Franks written instructions are also excellent, but a picture is worth a thousand words, and he updated some of the information.

And Dick, I do remember meeting you and your presentation at Denver. Glad to hear you have stuck with the Pacer and are still flying.

Take care.

Tom Anderson